The present invention relates to a method for applying resin on a connecting portion with a substrate of a panel, for the purpose of strengthening the connecting substrate connected to the panel for display, in particular in a liquid crystal display apparatus and/or a plasma display apparatus, etc., and it also relates to a manufacturing method of the panel for display, on which the resin is applied in such the manner, and further to an apparatus for applying the resin onto the connecting portion with the substrate of the panel.
Conventionally, a panel for display is constructed to be a liquid crystal cell of enclosing or encapsulating liquid crystal between two (2) pieces of glass substrates, which are disposed vertically. Between those two (2) pieces of the glass substrates building up the liquid crystal cell, the one of glass plates (being called by a lower substrate, normally) is made larger in sizes thereof than the other glass plate (being called by an upper substrate, with respect to the lower substrate), and onto two (2) sides of the lower substrate are connected circuit boards for driving thereof. Though each of the circuit boards is constructed with a printed circuit board (PCB), however for the purpose of limiting width of a frame within the liquid crystal display apparatus, it is attached with bending the printed circuit board. For this reason, connection between the liquid crystal cell and the printed circuit board is made by means of a flexible board, however as such the flexible board, there are various kinds, including one mounting ICs thereon, and one, on which only wiring patterns are provided, while mounting the ICs on the lower substrate thereof, etc.
FIG. 3 shows the structure, in which the flexible board mounting the ICs thereon is connected between the liquid crystal cell and the printed circuit board. In the figure, a reference numeral 1 indicates the liquid crystal cell, and this liquid crystal cell 1 has a lower substrate 2 and an upper substrate 3, both of which are made from glass substrates. For example, in a liquid crystal display of TFT type, the lower substrate 2 is a TFT substrate, while the upper substrate 3 a color filer. And, between both of those substrates 2 and 3 is enclosed or encapsulated liquid crystal. On the lower substrate 2 are formed transistors in a matrix manner, and for drawing out wirings 7 (see FIG. 4) connected with those transistors, it is expanded or projected only by a predetermined width from the upper substrate 3, at least on the two (2) sides thereof, neighboring with each other. To each of those wirings 7 is electrically connected with an electrode 8 (see FIG. 4) provided on the flexible board 4 mounting an IC 4a thereon. And, to electrodes on the other side of the flexible board 4 is connected a printed circuit board 5. Herein, the wirings 7 of the lower board 2 are formed as a group, being made up with a predetermined number thereof, and the flexible boards 4 are attached in a plural number thereof for each of those wiring groups.
Upon attaching each of the flexible boards 4 onto the lower board 2, as shown in FIG. 4, for the purpose of connecting the electrodes 8 provided on the flexible board 4 to the wirings 7 formed on the lower substrate 2, electrically, it is conducted through a ACF tape 6. The ACF tape 6 is made by dispersing minute conductive particles 6a on adhesive binder resin 6b, and this ACF tape 6 is pasted on the lower substrate 2, in advance, thereby covering over a portion of the wirings 7. Then, the flexible board 4 is positioned with respect to the lower substrate 2, and is attached on the ACF tape, and further the thermo-compression bonding is conducted thereon. With this, the binder resin 6b is thermally cured, and thereby the flexible board 4 is fixed onto the lower substrate 2, and also the conductive particles 6a are put between the wiring 7 and the electrode 8, thereby making up electrical connection between them.
Herein, almost of a part of the projection portion 2a of the lower substrate 2, which builds up the liquid crystal cell 1, is covered by the flexible boards 4, however a gap is produced somewhat between an edge portion of the flexible board 4 and an edge portion of the upper substrate 3. Covering the portion of that gap by resin enables to protect the wirings 7 and the electrodes 8, thereby obtaining measure for preventing foreign matters or the like from entering into from the gap defined therebetween. In more details, with disposing a dispenser having a needle-like nozzle directing to a corner portion between the projection portion 2a of the lower substrate 2 and the edge portion of the upper substrate 3 in the liquid crystal cell 1, dissolved resin is applied from the nozzle to the corner portion mentioned above while moving the liquid crystal cell 1 and the nozzle, relatively, and then the resin is cured through air drying or under the ultraviolet (UV) lights, etc.
Herein, in the liquid crystal cell, conventionally, it is already known such the structure, such as in Japanese Patent Laying-Open No. 11-30524 (1999), for example, in particular on page 4 and in FIG. 1 thereof <Patent Document 1>, that the resin is applied, not between the lower substrate and the flexible board, but at the corner portion of connecting portion between the upper substrate and the lower substrate, with using the dispenser, while positioning the needle constructing the dispenser under the condition of non-contact with the corner portion of the upper and lower substrates, and then the needle is moved while supplying the resin thereon.
However, since the ACF tape 6 has the predetermined size of width, then under the condition where it is pasted on the lower substrate 2, and therefore it cannot reach to the edge portion of the lower substrate 2. The flexible board 4 is piled upon the lower substrate 2, and a middle portion of the piled-up is adhered fixedly by the ACF tape 6, however there are produced still potions at both sides of the fixing portion, where it is only in contact with the lower substrate 2. For this reason, there is possibility that the flexible board 4 floats up from the surface of the lower substrate 2, thereby bringing about probability that foreign matters are mixed into therebeween, or that the flexible board 4 or the printed circuit board 5 connected with the flexible board 4 is exfoliated by an external force acting thereon, etc.
For the above reasons, it is preferable that the resin is supplied to the corner portion defined by the lower surface of the flexible board 4 and the edge portion of the lower substrate 2, so that the flexible board 4 will not rise up from the lower substrate 2. However, in case of trying to supply the resin by using such the dispenser, as was mentioned previously, first the needle-like nozzle is positioned at the corner portion of the upper substrate 3 on the surface side of the lower substrate 2, so as to supply the dissolved resin thereto, and thereafter the liquid crystal cell 1 is turned upside down, so that the needle-like nozzle is directed to between the edge portion of the lower substrate 2 and the lower surface of the flexible boards, to supply the dissolved resin from that nozzle.
However, with such the method as was mentioned above, it is necessary to turn the liquid crystal cell 1 from the condition that the lower substrate 2 is positioned below into the condition that it comes upward, once, to supply the resin thereupon, and thereafter it must be turned over, again, so that the upper substrate 3 comes above. Accordingly, it needs a mechanism for turning-over the liquid crystal cell 1, and therefore has a drawback that, not only being complex in the structure thereof, but also that it takes a long time for processing, etc.